1. Field of the Invention
This invention relates to microsurgical instruments. More particularly, the present invention relates to microsurgical instruments having end effectors mounted on a clevis coupled to an actuation means by a flexible coil where the clevis is rotatable relative to the flexible coil.
2. State of the Art
Most microsurgical instruments used in laparoscopic and endoscopic procedures include a pair of end effectors (cutters, dissectors, extractors, or the like) which are mounted on a clevis, where the clevis is coupled to the distal end of a tube. Proximal ends of the end effectors are often coupled to a push rod which extends through the tube. A handle with an actuation means coupled to the proximal ends of the tube and the push rod is typically used to allow the practitioner to move the push rod relative to the tube, thereby opening and closing the end effectors. In some microsurgical instruments, the tube and push rod are rigid members, such as in parent application Ser. No. 07/989,984. In other instruments, the "tube" is a long flexible coil and the "push rod" is one or more flexible wires such as in parent application Ser. No. 08/042,606.
Instruments utilizing a rigid tube and push rod are typically relatively short and are introduced into the body through a trocar tube. The practitioner views the surgical site through an optical device which is inserted in another trocar tube and "steers" the end effectors to the surgical site by angling the handle of the rigid instrument, and thereby angling the entire instrument. Parent application Ser. No. 07/989,984 discloses means for rotating the end effectors by rotating the rigid tube relative to the handle. This permits the practitioner to adjust the rotational position of the end effectors without changing the rotational position of the handle.
Instruments utilizing a flexible coil and pull wire(s) are typically relatively long and are introduced into the body through the narrow lumen of an endoscope. The practitioner views the surgical site through the endoscope and inserts the long flexible coil of the instrument through the narrow lumen of the endoscope so that the end effectors extend beyond the distal end of the endoscope. Since the flexible coil cannot be steered, the practitioner steers the end effectors to the surgical site by steering the endoscope. The endoscope is typically relatively long and often follows a tortuous path to the surgical site. Although the endoscope can be steered, its tortuous path makes it impossible to rotate. Moreover, because the flexible coil of the surgical instrument is, by nature, torsionally resilient, any attempt to rotate the end effectors by rotating the coil will at best result in a jerking movement of the end effectors. At worst, the coil will deform without effecting any rotation of the end effectors at all.